1. Field of the Invention
The present invention relates to improvement of an automatic document feeding apparatus mounted on a recording apparatus of an electrophotographic reproducing machine and others.
2. Description of the Prior Art
The automatic document feeding apparatus is generally mounted for use on a document glass plate (platen glass). In a reproducing machine using a movable optical system on which this automatic document feeding apparatus is mounted, documents in sheets (hereinafter referred to simply as documents) of standard sizes (for example, JIS Standard A series, B series, or USA Standard sizes) are stacked on a document stacker (stacking section), and each sheet of the documents is fed out one by one from the stack by feed rollers and others of the automatic document feeding apparatus and is carried by a carrier belt onto the document glass plate where exposures of a given number of copies are conducted with an exposure lamp equipped in the body of the reproducing machine. Then, each of the documents is delivered onto a document delivery tray.
Conventionally, in such an automatic document feeding apparatus, the operation of replacing documents on the document glass plate is possible only for the documents having standard sizes such as series A, B, and others. Accordingly, the control can be applicable only to the documents of these standards. Also, the next document is fed out from the stack after a delivery sensor has detected the delivery of the preceding document from the document glass plate. Then, this next document is carried to the document glass plate and placed at a given position thereon. Thus, it takes a long time to complete replacing the document. Hence, the productivity of copying is lowered because a considerably long time is necessary for performing copying operation, and further it is impossible to reproduce documents of non-standard sizes.
However, in a case where documents are automatically fed and delivered onto the document glass plate for replacement using an automatic document feeding apparatus, the productivity of copying documents becomes 100% and no wasteful time is consumed, if the replacement of the documents is performed during the period in which the scanning optical system is returned to its home position.
In order to materialize this, it is necessary to carry the document at a high speed from the position for prevention of double-feed in the stacking section to the position where the document is stopped on the document glass plate.
However, carrying a document at a high speed causes various problems to arise, such as the necessity of using a larger driving motor, the increase in power consumption, the higher possibility of damages on documents, the lower performance of document separation. There is some apparatus in which when a document is automatically fed and delivered onto the document glass plate for replacement by the automatic document feeding apparatus, the feeding is performed during the period of exposure or during the period in which the scanning optical system returns to its home position to eliminate wasteful consumption of time. However, anyone of the automatic document feeding apparatuses is structured and controlled to handle only the documents of standard sizes. Hence, there is a problem that documents of sizes other than the standard ones (hereinafter referred to as non-standard standard sizes) cannot be handled by the automatic document feeding apparatuses.